Ecrh With 10 Gyrotrons At W7-X - Achievements And Enhancements

Electron Cyclotron Resonance Heating (ECRH) was the main heating system during the operation campaign OP1.2b in 2018 of the W7-X stellarator Hi. The steady state capable ECRH system was used for plasma start-up, X-mode and 0-mode heating as well as current drive (ECCD). The ECRU plant is equipped with 10 operational 140 GHz gyrotrons and a quasi-optical transmission line, which is operated under standard atmosphere conditions. The achieved plasma parameters with respect to the performance of the ECRU plant and prospective enhancements will be discussed.